Sisters relationship

I have two daughters: a nine-year-old and a seven years old. The girls can’t be more different and opposite to each other. The older one is bossy and firm. The younger one is flexible and wants to please. The biggest challenge they face is that the older one can’t accept a “No” answer from the younger one. And she is usually pushing boundaries. The younger one doesn’t know how to problem solve with the oldest because the oldest wants to get her way, and so the youngest ends up telling on her, and that hurts their relationship.
The oldest also has a little bit of an attitude problem. She is raising her voice, rolling her eyes, and not being open to listening to what other people have to say.
How do I encourage the younger one to talk and express herself? How do I teach the older one to stay open to new ideas and hear the people around her?
I need to prove to them that this is going to help them and it is in their best interest.
What can I do to help them get a better balance between each other?

My husband and I are almost the same. I am flexible, and he is firm. I started to be more rigid, and he doesn’t like it. He feels like he is losing control and is scared I am overruling him. He is also struggling to accept NO answers from me.
Please help!
Thank you